Valve lash is one factor which determines how far the intake and exhaust valves will open into the cylinder.

If the valve clearance is too large, part of the lift of the camshaft will be used up in removing the excessive clearance, thus the valves will not be opened far enough. This condition has two effects, the valve train components will emit a tapping noise as they take up the excessive clearance, and the engine will perform poorly, since the less the intake valves open, the smaller the amount of air/fuel mixture admitted to the cylinders will be. The less the exhaust valves open, the greater the back-pressure in the cylinder which prevents the proper air/fuel mixture from entering the cylinder.

If the valve clearance is too small, the intake and exhaust valves will not fully seat on the cylinder head when they close. When a valve seats on the cylinder head it does two things; it seals the combustion chamber so none of the gases in the cylinder can escape and it cools itself by transferring some of the heat it absorbed from the combustion process through the cylinder head and into the engine cooling system. Therefore, if the valve clearance is too small, the engine will run poorly (due to gases escaping from the combustion chamber), and the valves will overheat and warp (since they cannot transfer heat unless they are touching the seat in the cylinder head).

Although Toyota recommends that the valve lash on certain models be set while the engine is running, we feel that for the average owner/mechanic it is more convenient to adjust the valves statically (engine off). Thus, running valve lash and adjustment procedures have been omitted from the guide. While all valve adjustments must be as accurate as possible, it is better to have the valve adjustment slightly loose than slightly tight, as burnt valves may result from overly tight adjustments.

ADJUSTMENT

8R-C and 18R-C

See Figures 8 and 9

Start the engine and allow it to run until it reaches normal operating temperature.

Be careful not to touch the engine as it will be quite hot.

Turn the engine off and remove the air cleaner assembly; the housing, hoses and bracket.

Remove any other hoses, cables or wires which are attached to the cylinder head cover.

Fig. Fig. 8: Valve adjusting sequence-8R-C and 18R-C engines

Fig. Fig. 9: Measure the clearance between the valve stem and adjusting nut--there should be a slight drag on the feeler gauge when properly adjusted

Check that the rocker arm bolts, the camshaft bearing cap bolts and the bearing cap union bolts are all tightened to the proper torque.

Set the No. 1 cylinder at TDC. Turn the crankshaft pulley until the pointer on the front cover lines up with the notch on the pulley.

Do not attempt to align the marks by cranking the engine with the starter. Valve clearances are checked with the engine stopped to prevent hot oil from being splashed out by the timing chain.

Check that the rocker arms on the No. 1 cylinder are loose and that the rockers on the No. 4 cylinder are tight. If not, rotate the crankshaft 360° until the marks line up again.

Valve clearance is checked between the end of the valve stem (it sticks out of the valve spring) and the bottom of the adjusting screw on the rocker arm.

Insert a feeler gauge and check for proper clearance on the No. 1 valve. To adjust, loosen the lock nut on the end of the rocker arm and turn the adjusting screw until the clearance is in accordance with the figures given in the "Tune-Up Specifications'' chart. Tighten the lock nut and recheck the clearance; there should be a slight drag felt when the feeler gauge is pulled through the gap. Repeat the procedure for the Nos. 2, 3, and 5 valves.

Turn the crankshaft 360° until the marks align with each other again and repeat Step 8 for valves 4, 6, 7, and 8.

Installation of the remaining components is in the reverse order of removal.

20R, 22R, 22R-E and 22R-TE

See Figures 10, 11 and 12

Disconnect the HAI and MC hoses, and follow Steps 1-7 of the 18R-C adjustment procedure. Disregard Step 5. When setting the No. 1 cylinder to TDC, align the notch on the crankshaft pulley with the
0
mark on the pointer scale.

Insert a feeler gauge and check for proper clearance on the No. 1 valve. To adjust, loosen the lock nut on the end of the rocker arm and turn the adjusting screw until the clearance is in accordance with the figures given in the "Tune-Up Specifications'' chart. Tighten the lock nut and recheck the clearance; there should be a slight drag felt when the feeler gauge is pulled through the gap. Repeat the procedure for Nos. 2, 4 and 6 valves.

Fig. Fig. 11: Turn the crankshaft 360 degrees and then adjust this set of valves-20R, 22R, 22R-E and 22R-TE engines

Fig. Fig. 12: Disconnect and plug the Hot Air Intake and Mixture Control (if equipped) hoses on the 22R-E engine before adjusting the valves

Turn the crankshaft 360° until the marks align with each other again and repeat Step 2 for valves 3, 5, 7, and 8.

Installation of the remaining components is in the reverse order of removal.

Valve adjustment determines how far the valves will open into the cylinder. If the clearance between the rocker arm and the valve is too great, part of the lift of the camshaft will be used up in removing the excess clearance; thus the valve will not open far enough into the cylinder. This will cause the valve to tap and likewise will cause the other valve train components to make an excessive amount of noise. Since the intake valves open less, the quality of air/fuel mixtures introduced into the cylinder will be less and the less the exhaust valves open, the greater the exhaust backpressure. These factors add up to a significant loss of power.

If the valve clearance is too small, the intake and exhaust valves will not fully seat on the cylinder head valve seats when they close. When the valve is tight against the valve seat it performs two functions: it seals the combustion chamber so that none of the gases in the cylinder can escape and the valve is cooled by the transference of heat to the cylinder head, which is in turn cooled by the cooling system of the engine. Therefore, if the valve clearance is too small the engine will run poorly due to the escape of gases from the combustion chambers on the compression and power strokes of the engine and the valves will overheat and burn because they cannot transfer heat properly.

Valve adjustments must be made as accurate as possible, however, it is better to have the valve clearance somewhat larger than smaller if there is any doubt.

3VZ-E Engines

See Figures 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 and 24

Remove the air intake chamber:

Tag and disconnect the throttle position sensor connector.

Tag and disconnect the canister vacuum hose from the throttle body.

Tag and disconnect the vacuum and fuel hoses from the pressure regulator.

Tag and disconnect the PCV hose at the union.

Tag and disconnect the No. 4 water by-pass hose from the union of the intake manifold.

Tag and disconnect the No. 5 water by-pass hose from the water by-pass pipe.

Tag and disconnect the cold start injector wire.

Tag and disconnect the vacuum hose at the fuel filter.

Remove the union bolt and two gaskets and then remove the cold start injector tube.

Tag and disconnect the EGR gas temperature sensor wire.

Tag and disconnect the EGR vacuum hoses at the air pipe and vacuum modulator.

On California trucks, remove the nut and bolt and then remove the intake chamber stay.

Remove the EGR valve with the pipes still connected.

Disconnect the No. 1 air hose at the reed valve.

Remove the six bolts and two nuts and lift off the air intake chamber and gasket.

Remove the engine wire.

Remove the cylinder head covers.

Remove the spark plugs.

Use a wrench and turn the crankshaft until the notch in the pulley aligns with the timing mark
0
of the No. 1 timing belt cover. This will insure that engine is at TDC.

Check that the valve lifters on the No. 1 cylinder are loose and those on No. 4 cylinder are tight. If not, turn the crankshaft one complete revolution (360°) and then realign the marks.

Using a flat feeler gauge measure the clearance between the camshaft lobe and the valve lifter. This measurement should correspond to the one given in the "Tune-Up Specifications'' chart. Check only the No. 6 intake valve and the No. 2 exhaust valve.

If the measurement is within specifications, go on to the next step. If not, record the measurement taken for each individual valve. They will be used later to determine the required replacement shim sizes.

Turn the crankshaft
1
/
3
of a revolution (120°) and measure the clearance at the No. 1 intake and the No. 3 exhaust valves. Record any measurement that is out of specification.

Turn the crankshaft
1
/
3
of a revolution (120°) and measure the clearance at the No. 2 intake and the No. 4 exhaust valves. Record any measurement that is out of specification.

Turn the crankshaft
1
/
3
of a revolution (120°) and measure the clearance at the No. 3 intake and the No. 5 exhaust valves. Record any measurement that is out of specification.

Turn the crankshaft
1
/
3
of a revolution (120°) and measure the clearance at the No. 4 intake and the No. 6 exhaust valves. Record any measurement that is out of specification.

Turn the crankshaft
1
/
3
of a revolution (120°) and measure the clearance at the No. 5 intake and the No. 1 exhaust valves. Record any measurement that is out of specification.

If the measurements for the previous six sets of valves are within specifications, you need go no further, the procedure is finished. If not, to Step 12.

Turn the crankshaft to position the intake camshaft lobe of the cylinder to be adjusted, upward.

Using a small awl, turn the valve lifter so that the notch is easily accessible.

Install SST No. 09248-55010 (the scissors type) on the lifter and then squeeze the handle so that the tool presses down the valve lifter evenly. Hold the valve lifter down with the single tool.

For easy removal of the shim, set the special tool on the lifter so there is adequate space in the removal direction.

Using a small screwdriver and a magnet, remove the valve shim.

Measure the thickness of the old shim with a micrometer. Locate that particular measurement in the "Installed Shim Thickness" column of the accompanying charts, then locate the previously recorded measurement (from Step 6-11) for that valve in the "Measured Clearance " column of the charts. Index the two columns to arrive at the proper replacement shim thickness.

Replacement shims are available in 25 sizes, in increments of 0.05mm, from 2.200mm to 3.400mm.

Install the new shim, remove the special tool and then recheck the valve clearance.

Install the spark plugs.

Install the cylinder head covers.

Install the engine wire.

Install the air intake chamber and then check the ignition timing and idle speed.

Start the engine and allow it to reach normal operating temperature (above 165°F).

Stop the engine. Remove the air cleaner assembly with related components. Remove any cables, hoses, wires, etc., which are attached to the valve cover and remove the valve cover.

Tighten the cylinder head bolts as detailed in
Engine & Engine Overhaul
. Also torque the manifold attaching nuts to 28-37 ft. lbs. for trucks outside of California, or 37-51 ft. lbs. for California trucks, and the rocker support fasteners to 15-21 ft. lbs. on 8mm bolts and 22-32 ft. lbs. on 10mm bolts.

Start the engine and adjust the idle speed as described in the following procedure.

Check the clearance between each of the rocker arms and valve stems while the engine is at slow idle, using a feeler gauge of the proper size (See the Tune-Up Specifications chart).

If the clearance is incorrect, loosen the locknut and turn the adjusting screw as required. Tighten the locknut and recheck the clearance.

After adjusting all of the valves, install the valve cover and any other components which were removed during Step 2.

Recheck the engine idle speed and adjust if necessary.

Fig. Fig. 25: Adjust these valves FIRST-F series engine

Fig. Fig. 26: Adjust these valves SECOND-F series engine

Fig. Fig. 27: Valve adjustment-F, 2F and 3F-E engine

1L, 2L and 2L-T Engines

See Figure 28

Fig. Fig. 28: Diesel valve adjustment

The valves are adjusted in basically the same manner as the 20R, 22R and 22R-E engines, in that the engine must be OFF during the adjustment and that the clearance is checked with a feeler gauge between the rocker arm and the valve stem end.

The engine must be at normal operating temperature to obtain the proper valve clearances.

Remove the valve cover and rotate the crankshaft to align the TDC mark on the crankshaft pulley with the corresponding pointer. The valves of the number one cylinder should be closed (rocker arms should feel loose). If the rocker arms of the number one cylinder are tight, rotate the engine another 360° and again align the TDC marks.

Adjust the clearances of the following valves:

No.1 cylinder: intake and exhaust

No.2 cylinder: intake

No.3 cylinder: exhaust

Rotate the crankshaft 360° and adjust the remaining valves:

No.2 cylinder: exhaust

No.3 cylinder: intake

No.4 cylinder: intake and exhaust

Remember that the cylinder numbering from the front of the engine to the rear is No. 1 through No. 4, and that the valve arrangement from the front of the engine is E-I-E-I-E-I-E-I, with E designating each exhaust valve and I designating each intake valve. Choose your specifications from the Diesel Tune-Up Chart accordingly.